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Message-ID: <89011ab8-0ec2-431d-8842-f3738870db36@intel.com>
Date: Mon, 2 Feb 2026 16:34:30 -0800
From: Jacob Keller <jacob.e.keller@...el.com>
To: Anshumali Gaur <agaur@...vell.com>
CC: <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Sunil Goutham
	<sgoutham@...vell.com>, Linu Cherian <lcherian@...vell.com>, Geetha sowjanya
	<gakula@...vell.com>, Jerin Jacob <jerinj@...vell.com>, hariprasad
	<hkelam@...vell.com>, Subbaraya Sundeep <sbhatta@...vell.com>, Andrew Lunn
	<andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>, "Eric
 Dumazet" <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>
Subject: Re:



On 2/2/2026 2:53 AM, Anshumali Gaur wrote:
> On 2026-01-29 at 23:02:43, Jacob Keller (jacob.e.keller@...el.com) wrote:
>>
>>
>> On 1/29/2026 1:19 AM, Anshumali Gaur wrote:
>>> When both AF and PF drivers are built as modules, the PF driver in the
>>> kexec kernel may probe before the AF driver is ready. This leads to
>>> a crash due to uninitialized hardware state.
>>>
>>> This patch ensures the PF driver properly detects and waits for AF
>>> driver readiness before proceeding with initialization.
>>>
>>
>> To me, the patch description is not sufficient to describe the what and why
>> of this change.
>>
>> Could you please provide a better explanation of how the addition of the
>> provided shutdown handler fixes initialization?
>>
> Hi Jacob,
> The issue being addressed here is specific to kexec and persistent AF
> hardware state across kernel transitions. When both AF and PF drivers
> are built as modules and a kexec kernel is performed, the PF driver in
> the new kernel may probe before the AF driver has completed probing and
> reinitializing the RVU hardware. In this scenario, the hardware state
> left behind by the AF driver in the old kernel is still visible to the
> PF driver in the new kernel resulting in crash due to stale state.
>>> Fixes: 54494aa5d1e6 ("octeontx2-af: Add Marvell OcteonTX2 RVU AF driver")
>>> Signed-off-by: Anshumali Gaur <agaur@...vell.com>
>>> ---
>>>    drivers/net/ethernet/marvell/octeontx2/af/rvu.c | 11 +++++++++++
>>>    1 file changed, 11 insertions(+)
>>>
>>> diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
>>> index 747fbdf2a908..8530df8b3fda 100644
>>> --- a/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
>>> +++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
>>> @@ -3632,11 +3632,22 @@ static void rvu_remove(struct pci_dev *pdev)
>>>    	devm_kfree(&pdev->dev, rvu);
>>>    }
>>> +static void rvu_shutdown(struct pci_dev *pdev)
>>> +{
>>> +	struct rvu *rvu = pci_get_drvdata(pdev);
>>> +
>>> +	if (!rvu)
>>> +		return;
>>> +
>>> +	rvu_clear_rvum_blk_revid(rvu);
>>
>> Here, I guess you are clearing some data about the device status. Does that
>> mean that when you initialize later you will wait for the AF driver to
>> finish probing and configure this? It would be nice to explain how this
>> change fixes initialization.
>>
> The RVUM block revision field acts as an implicit indication that the AF
> driver has completed its initialization. If this value is left uncleared
> during kexec kernel booting, the PF driver may observe a non-zero/valid
> RVUM block revision and incorrectly assume that the AF is already
> initialized and ready, even though the AF driver in the kexec kernel has
> not yet probed. This leads to PF initialization proceeding against
> partially initialized hardware, resulting in a crash.

Makes sense. When shutting down you need to explicitly clear the stale 
data so that booting up (without a powercycle as in the kexec case) does 
not lead to stale data.

I'd appreciate a little more of this detail in the commit message 
personally. However, functionally it makes sense, so:

Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>